The type II secretion system: biogenesis, molecular architecture and mechanism

Korotkov, Konstantin V.; Sandkvist, Maria; Hól, Wim G. J.

doi:10.1038/nrmicro2762

Cited by 424 publications

(434 citation statements)

References 164 publications

(262 reference statements)

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“…The T2S system is broadly distributed in eubacteria, where it exports fully folded proteins and protein complexes from the periplasm across the outer membrane, where they remain associated with the cell surface or are released (98,99,205,237). This pathway allows for the secretion of proteins folded with cofactors or associated with chaperones or inhibitory peptides that are released upon secretion.…”

Section: Protein Secretionmentioning

confidence: 99%

“…Those data have been invaluable for the refinement of theories about the mechanism of fiber assembly and function. Other key information came from protein-protein interaction studies that showed the specific pattern of interactions, both stable and transient, between various minor pseudopilins, between pseudopilins and components of the assembly system, and even with the T2S substrates (124,125,236,237,244,329). Among the important questions that remain to be answered is how the substrates of T2S (and T4P, where they are involved in secretion) are recognized against the background of myriad periplasmic proteins.…”

Section: Protein Secretionmentioning

confidence: 99%

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Type IV Pilin Proteins: Versatile Molecular Modules

Giltner

Nguyen

Burrows

2012

Microbiol Mol Biol Rev

386

519

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SUMMARYType IV pili (T4P) are multifunctional protein fibers produced on the surfaces of a wide variety of bacteria and archaea. The major subunit of T4P is the type IV pilin, and structurally related proteins are found as components of the type II secretion (T2S) system, where they are called pseudopilins; of DNA uptake/competence systems in both Gram-negative and Gram-positive species; and of flagella, pili, and sugar-binding systems in the archaea. This broad distribution of a single protein family implies both a common evolutionary origin and a highly adaptable functional plan. The type IV pilin is a remarkably versatile architectural module that has been adopted widely for a variety of functions, including motility, attachment to chemically diverse surfaces, electrical conductance, acquisition of DNA, and secretion of a broad range of structurally distinct protein substrates. In this review, we consider recent advances in this research area, from structural revelations to insights into diversity, posttranslational modifications, regulation, and function.

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Section: Protein Secretionmentioning

confidence: 99%

Section: Protein Secretionmentioning

confidence: 99%

Type IV Pilin Proteins: Versatile Molecular Modules

Giltner

Nguyen

Burrows

2012

Microbiol Mol Biol Rev

386

519

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“…PCC6803 | twitching motility | phototaxis | signal transduction | fluorescence T ype IV pili (T4P) are fascinating supermolecular machines that drive twitching motility, protein secretion, and DNA uptake in prokaryotes (1). Twitching motility is now widely accepted as a form of bacterial translocation involving repetition of the cycle of extension and retraction of the pili (2, 3) (Fig.…”

mentioning

confidence: 99%

Asymmetric distribution of type IV pili triggered by directional light in unicellular cyanobacteria

Nakane

Nishizaka

2017

Proc. Natl. Acad. Sci. U.S.A.

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The type IV pili (T4P) system is a supermolecular machine observed in prokaryotes. Cells repeat the cycle of T4P extension, surface attachment, and retraction to drive twitching motility. Although the properties of T4P as a motor have been scrutinized with biophysics techniques, the mechanism of regulation remains unclear. Here we provided the framework of the T4P dynamics at the single-cell level in Synechocystis sp. PCC6803, which can recognize light direction. We demonstrated that the dynamics was detected by fluorescent beads under an optical microscope and controlled by blue light that induces negative phototaxis; extension and retraction of T4P was activated at the forward side of lateral illumination to move away from the light source. Additionally, we directly visualized each pilus by fluorescent labeling, allowing us to quantify their asymmetric distribution. Finally, quantitative analyses of cell tracking indicated that T4P was generated uniformly within 0.2 min after blue-light exposure, and within the next 1 min the activation became asymmetric along the light axis to achieve directional cell motility; this process was mediated by the photo-sensing protein, PixD. This sequential process provides clues toward a general regulation mechanism of T4P system, which might be essentially common between archaella and other secretion apparatuses.Synechocystis sp. PCC6803 | twitching motility | phototaxis | signal transduction | fluorescence T ype IV pili (T4P) are fascinating supermolecular machines that drive twitching motility, protein secretion, and DNA uptake in prokaryotes (1). Twitching motility is now widely accepted as a form of bacterial translocation involving repetition of the cycle of extension and retraction of the pili (2, 3) (Fig. 1A), which is powered by assembly and disassembly ATPase at the base of helical pilus fibers (4). The mechanical response of a single pilus has been scrutinized in great detail using biophysical approaches such as optical tweezers methodology in Neisseria gonorrheae (3, 5-7), although the dynamic properties resulting from the response to various environmental signals remain less understood than those of bacterial flagella. T4P is also evolutionarily and structurally related to flagella in archaea, which have recently been designated archaella (8-11). Although newly developed techniques enable us to examine the dynamic properties of the machinery, little is known about the regulation mechanism of T4P because tens of components cooperate to orchestrate the dynamics of both the archaella and T4P system. Such complexity hampers the design of an experimental setup with quantitative and reproducible evaluations.To address how the T4P system is activated or repressed by environmental signals over a short timescale, we here used Synechocystis sp. PCC6803, a model cyanobacteria (12)(13)(14). This species exhibits T4P-dependent twitching motility on surfaces such as soft-agar plates at speeds of a few micrometers per minute, and the cell motility direction is regulated both posi...

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“…Although the genes essential for transformation are well described for various species, little is known about the molecular mechanism driving DNA import (6,13). The transformation system shares several structural and functional features with the type 4 pilus system (T4PS) and the type 2 secretion system (T2SS) (14) (Fig. S1).…”

mentioning

confidence: 99%

Kinetics of DNA uptake during transformation provide evidence for a translocation ratchet mechanism

Hepp

Maier

2016

Proc. Natl. Acad. Sci. U.S.A.

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Horizontal gene transfer can speed up adaptive evolution and support chromosomal DNA repair. A particularly widespread mechanism of gene transfer is transformation. The initial step to transformation, namely the uptake of DNA from the environment, is supported by the type IV pilus system in most species. However, the molecular mechanism of DNA uptake remains elusive. Here, we used singlemolecule techniques for characterizing the force-dependent velocity of DNA uptake by Neisseria gonorrhoeae. We found that the DNA uptake velocity depends on the concentration of the periplasmic DNA-binding protein ComE, indicating that ComE is directly involved in the uptake process. The velocity-force relation of DNA uptake is in very good agreement with a translocation ratchet model where binding of chaperones in the periplasm biases DNA diffusion through a membrane pore in the direction of uptake. The model yields a speed of DNA uptake of 900 bp·s −1 and a reversal force of 17 pN. Moreover, by comparing the velocityforce relation of DNA uptake and type IV pilus retraction, we can exclude pilus retraction as a mechanism for DNA uptake. In conclusion, our data strongly support the model of a translocation ratchet with ComE acting as a ratcheting chaperone.

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The type II secretion system: biogenesis, molecular architecture and mechanism

Cited by 424 publications

References 164 publications

Type IV Pilin Proteins: Versatile Molecular Modules

Type IV Pilin Proteins: Versatile Molecular Modules

Asymmetric distribution of type IV pili triggered by directional light in unicellular cyanobacteria

Kinetics of DNA uptake during transformation provide evidence for a translocation ratchet mechanism

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